Fig. 3.

– Schematically representation of the two histopathological phases of DAD. A - The first or exudative phase constitutes alveolar edema, neutrophil infiltration in the intra-alveolar space and mainly by hyaline membrane formed by fibrin polymerization contained in the plasma liquid that leaked into the interstitial/alveolar space, being recognized as DAD hallmark; B - The second or proliferative phase is described essentially by an intense fibroblast/myofibroblast recruitment and proliferation, with subsequent extracellular matrix deposition. Over time and together with the fibrotic deposition, there is also the reepithelization by type I and II pneumocytes.